Electric air heater



Dec. 2 8, 1948.

c. OSTERHELD ELECTRIC AIR HEATER Filed Dec. 19,- 1946 INVENTOR. CLARK M. OSTERHELD g/w a Patented Dec. 28, 1948 'U'NTl .S TAT-ES FPATTE N T F F lC E ELECTRIC AIR HEATER -fClark Mnosterheld, Stoughton, Wis., assignor-to -.McGr-aw Electric Company, -'Elgin, =Ill., a corporation of Delaware Application December 19, 1946, Serial No. 717,273

1 Claim. "1

My invention relates to electric heaters and particularly to electric-air-heaters.

An object of my invention is to provide a relatively simple form and construction of electric air heater.

Another object of m invention is to provide an electric air heaterthatshall-use a novel form of electric insulation.

Other objects of my invention will either "be apparent from a description of several modifications of electric air heaters embodying my invention or will be pointed out during the course of such description and be particularly set forth in the appended claim.

In the drawings,

Figure 1 is a perspective view with a part cut away of an electric air heater embodying my invention,

Fig. 2 is a fragmentary front elevational view of a modified form of support for the resistor of my improved air heater,

Fig. 3 is a view in end elevation of the parts shown in Fig. 2,

Fig. 4 is a fragmentary front elevational view of a still further modification of the support of my improved air heater, and,

Fig. 5 is a view in perspective of a supporting member for my heating unit.

Referring first of all to Fig. l of the drawings, I have there shown an assembled electric air heater I embodying a base 13 which is shown as a substantially rectangular plastic block having downwardly projecting supporting members I5. I provide an outer casing comprising a sheet-metal wall ll, which sheet metal is of such extent in area as to provide two side walls as well as a perforated top wall. I provide also a pair of end Walls 19 which may 'be secured to the side and top walls as by a plurality of screws 2!.

Within the casing comprising the bottom support l3 and the walls I! and I!) are positioned a plurality of supporting blocks 23 which are preferably of a refractory electric-insulating material such as porcelain and which are provided with a recess 25 extending into one of the side edges of block 23. Any suitable or desirable means for holding the blocks 23 against the upper and the lower edges of end walls l9 may be provided, but are not shown.

The electric heating unit embodying my invention comprises a relatively thin sheet of metal 22', the corners of which are adapted to fit into the slots 25, to thereby hold the sheet in upright position. The upper and lower edges of 'form'lysspaced relativelysmallrecesses29. Imay make :the sheetZl of any standard metal 'ness 'of sheet .21 .on the order of .035". I have giveniapreferred dimension'I do not desire to be limited thereto since I may use sheet thick.

2 sheet :21 are provided with a plurality of uni- -While Iprefer'to' use aluminum and to make the thick- While metal havinga'thi'ckness'of from103" to .04" I 'providea resistance conductor 3! in the form of a strip of resistance metal, preferably aluminum, and Wind the same helically around the sheet 21 and in the respective recesses 29. While I have not shown any terminals for the resistance conductor 31 it is to be understood that a pair of terminals are secured to one endmember l9 so that a connecting plug on a twin conductor cord may be used to cause energization of the heater l l.

The entire surface of resistance conductor 3| as well as of the sheet 21 may be covered with an integral, inorganic, heat-conducting, hightemperature resisting and electric insulating coating having a thickness on the order of .001". While I have given a specific thickness of the coating, I do not desire to be limited thereto since the thickness of this coating may vary between the limits of '.0005" and .0015". The method disclosed in U. S. Patent #1,526,127 may be used to provide this coating although any other means now known may be provided.

Referring now to Fig. 2 of the drawings, I have there shown a modified form of heating unit embodying a sheet 33 which is preferably made of relatively thin aluminum, the aluminum having a thickness on the order of .035 with allowable variations of from .03" to .04". On each of two opposite sides of sheet 33 I provide a relatively thick strip 35 of mica, each strip having a plurality of recesses 37 in its outer edge, each mica strip being secured in its proper operative position at the edge of one side of sheet 33 by a plurality of rivets 39 or other suitable securing means. I provide a resistance strip 4| which may be wound around the strip 33 and in the recesses 31, the strip being wound in a substantially helical form along the entire width of the sheet 33. While no terminals are shown it is to be understood that such are provided.

Referring now to Fig. l of the drawings, I have there illustrated a still further modification comprising a sheet 43 having a plurality of relatively small openings or slots provided therein within each edge. A resistance strip 41 is adapted to be Wound through the slots 45 from one side of strip 43 to the other, the resistance 3 conductor 41 extending across in a helical shape substantially the entire width of sheet 43.

I desire it to be understood that sheets 21, 33 and 43, as well as the resistance strips 3|, 3'! and 41, may be coated with the hereinbefore described anodic coating. While I may coat the entire outer surface of sheets 21, 33 and 43, as well as of resistance strips 3|, 3! and 41, I may coat a selected one of such elements particularly in the design shown in Fig. 2 of the drawings.

The amount of energy translated into heat in resistance strips 3|, 31 and 41 may be made any desirable or predetermined value as by using a predetermined thickness of strip as Well as a predetermined width of strip, as well as a predetermined number of turns around the supporting sheet.

The device embodying my invention thus provides a novel form of electric-insulation, which insulation is integral with either the resistance conductor or with the supporting sheet, or both, and in case a relatively small amount of energy is to be translated into heat, providing large gaps between adjacent turns of the resistance strip,

m improved heater will be available to heat substantially all of the surface of sheet 21, 33, or 43.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof and I desire that all such modifications coming clearly within the scope of the appended claim shall be considered a part of my invention.

I claim as my invention:

An electric air heater comprising a casing, a relatively thin sheet of metal supported in a substantially vertical position in and by said casing, a plurality of horizontally alined openings adjacent the upper and the lower edges of said sheet of metal and a metallic resistance conductor wound helically through said openings, said sheet of metal and said resistance conductor having on their entire outer surface an integral, inorganic, heat-conducting, high-temperature-resisting and electric-insulating coating.

CLARK M. OSTERHELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 507,941 Snee Oct. 31, 1893 825,211 Heath July 3, 1906 1,050,912 Bolling Jan, 21, 1913 1,712,010 Somes May 7, 1929 2,228,101 Willmann Jan. 7, 1941 2,362,152 Osterheld Nov. 7, 1944 

